Study of focused ultrasound tissue damage using MRI and histology

This paper reports on an experimental study of in vivo tissue damage in the rabbit brain with focused ultrasound (FUS) using magnetic resonance imagin g (MRI) and histopathological analysis. Ten ultrasonic lesions (tissue dama ge) were created in five rabbits using a focused ultrasound beam of 1.5 MHz , electrical power input to the transducer of 70-85 W, and an exposure dura tion of 15-20 seconds. T1- and T2-weighted fast spin-echo (FSE) and Fluid a ttenuated inversion recovery (FLAIR) sequences were used to detect the ultr asonic lesions after treatment, Imaging was performed for 4-8 hours after t reatment, after which the animals were immediately sacrificed. Ultrasonic l esion diameter was measured on MRI and histological sections after correcti on for tissue shrinkage during the histological processing. The T1-weighted images showed lesions poorly, whereas both T2-weighted and FLAIR images sh owed lesions clearly, The lesion diameters on both T2 and FLAIR imaging cor related web with measurements from histology. The time delay before lesions appeared on T2-weighted imaging was 15 minutes to 1 hour, depending on the exposure location in the brain. (C) 1999 Wiley-Liss, Inc.